This application relates to whispering gallery mode (WGM) resonators and their applications.
The optical resonators may be configured as optical whispering-gallery-mode (“WGM”) resonators which support a special set of resonator modes known as whispering gallery (“WG”) modes. These WG modes represent optical fields confined in an interior region close to the surface of the resonator due to the total internal reflection at the boundary. For example, a dielectric sphere may be used to form a WGM resonator where WGM modes represent optical fields confined in an interior region close to the surface of the sphere around its equator due to the total internal reflection at the sphere boundary. Quartz microspheres with diameters on the order of 10˜102 microns have been used to form compact optical resonators with Q values greater than 109. Such hi-Q WGM resonators may be used to produce oscillation signals with high spectral purity and low noise. Optical energy, once coupled into a whispering gallery mode, can circulate at or near the sphere equator over a long photon life time.